Index: memory_manager.cpp
===================================================================
--- lib/drivers/libusb/memory_manager.cpp	(revision 70372)
+++ lib/drivers/libusb/memory_manager.cpp	(working copy)
@@ -132,7 +132,7 @@
     OUT PVOID *OutVirtualAddress,
     OUT PPHYSICAL_ADDRESS OutPhysicalAddress)
 {
-    ULONG Length, BlockCount, FreeIndex, StartPage, EndPage;
+    ULONG Length, BlockCount, FreeIndex, LastIndex, StartPage, EndPage;
     KIRQL OldLevel;
     ULONG BlocksPerPage;
 
@@ -166,11 +166,13 @@
     // helper variable
     //
     BlocksPerPage = PAGE_SIZE / m_BlockSize;
+    ASSERT(BlockCount <= BlocksPerPage);
 
     //
     // start search
     //
     FreeIndex = 0;
+    LastIndex = MAXULONG;
     do
     {
         //
@@ -190,10 +192,21 @@
         }
 
         //
-        // check that the allocation does not spawn over page boundaries
+        // did we wrap over to the start of the bitmap?
         //
-        StartPage = (FreeIndex * m_BlockSize);
-        StartPage = (StartPage != 0 ? StartPage / PAGE_SIZE : 0);
+        if (FreeIndex <= LastIndex && LastIndex != MAXULONG)
+        {
+            //
+            // no free block found;
+            //
+            FreeIndex = MAXULONG;
+            break;
+        }
+
+        //
+        // check that the allocation does not span over page boundaries
+        //
+        StartPage = (FreeIndex * m_BlockSize) / PAGE_SIZE;
         EndPage = ((FreeIndex + BlockCount) * m_BlockSize) / PAGE_SIZE;
 
         //
@@ -227,13 +240,13 @@
         else
         {
             //
-            // request spawned over page boundary
+            // request spanned over page boundary
             // restart search on next page
             //
-            FreeIndex = (EndPage *  PAGE_SIZE) / m_BlockSize;
+            LastIndex = FreeIndex;
+            FreeIndex = (EndPage * PAGE_SIZE) / m_BlockSize;
         }
-    }
-    while(TRUE);
+    } while (TRUE);
 
     //
     // release lock
@@ -248,7 +261,7 @@
         //
         // failed to allocate block, requestor must retry
         //
-        return STATUS_UNSUCCESSFUL;
+        return STATUS_INSUFFICIENT_RESOURCES;
     }
 
     //